Complete comprehensive Codex → LLMX branding update

Fixed all remaining user-facing "Codex" references across entire codebase:
- Updated all UI strings and error messages
- Fixed GitHub issue templates and workflows
- Updated MCP server tool descriptions and error messages
- Fixed all test messages and comments
- Updated documentation comments
- Changed auth keyring service name to "LLMX Auth"

Reduced from 201 occurrences to only code identifiers (struct/type names).
Changes span 78 files across Rust, Python, YAML, and JSON.

🤖 Generated with Claude Code

Co-Authored-By: Claude <noreply@anthropic.com>

.github/ISSUE_TEMPLATE/2-bug-report.yml

@@ -7,18 +7,18 @@ body:
   - type: markdown
     attributes:
       value: |
-        Thank you for submitting a bug report! It helps make Codex better for everyone.
+        Thank you for submitting a bug report! It helps make LLMX better for everyone.
 
-        If you need help or support using Codex, and are not reporting a bug, please post on [codex/discussions](https://github.com/openai/codex/discussions), where you can ask questions or engage with others on ideas for how to improve codex.
+        If you need help or support using LLMX, and are not reporting a bug, please post on [llmx/discussions](https://github.com/valknar/llmx/discussions), where you can ask questions or engage with others on ideas for how to improve llmx.
 
-        Make sure you are running the [latest](https://npmjs.com/package/@openai/codex) version of Codex CLI. The bug you are experiencing may already have been fixed.
+        Make sure you are running the [latest](https://npmjs.com/package/@llmx/llmx) version of LLMX CLI. The bug you are experiencing may already have been fixed.
 
         Please try to include as much information as possible.
 
   - type: input
     id: version
     attributes:
-      label: What version of Codex is running?
+      label: What version of LLMX is running?
       description: Copy the output of `codex --version`
     validations:
       required: true